1. Field of the Invention
The present invention generally relates to a power grass mower. More particularly, the invention relates to a power-operated grass-mowing machine as a small-sized working machine of the type which employs engine power to drive a cutter for cutting coarse grass.
2. Description of Relevant Art
For the cutting of coarse grass growing on the slope of a footpath or ridge between paddy fields or plowed fields, ordinary mobile type power lawn mowers or similar power grass mowers are difficult to use because the ground to be mowed is sloping. For that reason, there are currently used power grass mowers of a shoulder-carry, hand-hold operation type in which a round saw-like cutter is provided at the distal end of an arm.
The shoulder-carry hand-hold operation type of power grass mower normally includes a prime-mover as a cutter-driving power source provided with accessories thereof which the operator carries on his or her back, and an arm which is relatively long and provided with the cutter which the operator manipulates using his or her hands. This type mower has however some disadvantages such as that the weight is a heavy burden for the operator, that the reaction of cutter rotation is directly transmitted to the operator and hence the operation is all the more difficult, that due to the heavy weight the operator becomes tired during a long work and that the difficulty of controlling operation with the hands makes it difficult to mow grass at an even level relative to the sloping ground.
Such or similar problems of the shoulder-carry hand-hold operation type power grass mower are found also in other cases than when mowing grass on the slope of foot paths or ridges between fields; exemplarily, in the mowing of grass on the side of a bank, as well as when mowing grass on sloping flanks.
In this respect, by Japanese Patent Application Lay-Open Print No. 58-81708, laid open on May 17, 1983, there has been proposed a ground type of power grass mower with a purpose of permitting the mowing of grass on a slope to be easily done without requiring the operator to carry on his or her back an engine for driving a cutter.
According to this Japanese Patent Application Lay-Open Print, the ground type power grass mower included a thick plate-like ground foot member, a rotary cutter and an engine both mounted on the ground foot member, a handle shaft connected at one end thereof to the engine and formed at the other end thereof as a grip for the operator to handle, and a support wheel fitted on the handle shaft. The ground foot member was adapted to rotate with power from the engine. The support wheel was positionally adjustable in the axial direction of the handle shaft.
With such constitution, the ground type power grass mower relieved the operator from being burdened with weighty things such as the engine. Further, in respect of this type of power grass mower, due to possible rotation of the ground foot member which had a smooth bottom face, the power grass mower was said to have reduced the friction relative to the ground, thereby enabling the operator to remove the mower with ease.
However, this power grass mower, which was not of a self-propelled travelling type, had still left on the operator a burden attendant on the movement of mower, as it had been experienced, particularly at slopes.
Moerover, when working with this power grass mower, in which the handle shaft was fixed to the engine as a body of the mower, in places where the sloping angle of the ground was within a certain range, the operator had to take an unnatural posture to hold the mower, which made it difficult for the operator to perform mowing work for a long while.
Incidentally, the aforementioned ordinary self-propelled type power lawn mowers and similar power grass mowers are currently put to practical use as a small-sized working machine that employs engine power to move while driving a cutter for mowing lawn or grass.
A typical type of those self-propelled power mowers includes a cutter housing which has a cutter of a rotary blade type accommodated therein for cutting grass and a grass cut provided at one side thereof for guiding cut grass, at this side, laterally and rearwardly. The cut grass is so guided at the same side as to be simply discharged in the rearward direction or to be received in a grass bag attached to the outlet of the grass duct.
Such self-propelled type conventional power mowers, which are small-sized and handy, are generally adapted to move in the forward direction only and thus, when trying to move back and forth to cut grass along neighboring lines, the mower needed to be completely turned 180.degree. at the forward end of each line.
Moreover, such conventional power mowers, though suitable for mowing work on flat places, are not adapted to cut grass in such places that are close to fence-like obstacles or at the inside of relatively narrow conduits or channels.
Further, in the use of such conventional power mowers, which have a cutter housing arranged at the bottom thereof and in which cut grass is guided to be discharged at either side of the cutter housing or received with a grass bag provided at the discharge side thereof, a further inconveniency is encountered when cutting grass such as weeds growing on the sides of footpaths or ridges between paddy or plowed fields or in ordinary agricultural fields or wasteland, such that the grass, generally grown tall at such places, may be forced down by, entirely giving way beneath, the cutter housing advancing to ride thereon and hence become difficult to cut neatly. In addition to that, the cut grass is not always needed to be discharged at the described one-side only: exemplarily, there being such a case to be observed at somewhere along a paddy field for example, that the cut grass had rather be thrown out in front or rear of the mower, to be left there as it withers, than being discharged into the paddy field; or in many cases, there being found such a tendency, at certain places or under certain conditions, that the cut grass is required to be dicharged at both sides of the mower, to be left there as it withers.
Incidentally, to overcome the necessity of turning the mower 180.degree. after moving each line of grass in back-and-forth mowing work, there has been disclosed a power mower, in U.S. Pat. No. 2,926,478 by I. Jepson, patented on Mar. 1, 1960, in which a handle shaft is positionally variable relative to a mower body including an engine and a cutter.
In the power mower according to the United States Patent by Jepson, the handle shaft was adapted to be voluntarily selectively pivotable about the mower body, in a vertical plane including the longitudinal centerline of the mower body. Further, in this power mower, which was of a handcart type, the mower body was supported with four ground wheels permitting the mower to move in the longitudinal direction only. With such arrangement, it was permitted to make the back-and-forth mowing work by pivoting the handle shaft frontwardly at the forward end of each mowing line, without the need of turing the mower itself at an angle of 180.degree..
However, like the ordinary mobile type power mower, the handcart type power mower according to the Unites States Patent by Jepson was not yet sufficiently adapted for use in the mowing work on sloping ground.
Particularly, for an operator standing on a footpath between fields and trying to mow grass growing on the side slopes of the footpath, it was very difficult to continuously perform mowing work with the power mower by Jepson which was substantially unable to be wheeled in parallel with the footpath. Moreover, even when trying to do work, directly standing on the side slope of such footpaths, the operator had to bear an extremely large weight burden from this power mower because it is not of a self-propelled travelling type.
The present invention has been achieved to effectively solve such problems of and favorably accomplish associated desiderata of, conventional power grass mowers, without following the constitution of the shoulder-carry, hand-hold operation type power grass mower which is inconvenient to operate.